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How do QR codes differ from barcodes? © Getty Images

How do QR codes differ from barcodes?

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These pixelated squares can hold more data than the zebra-striped pattern of a classic bar code.

Asked by: Helena Cooper, Salisbury


Barcodes come in all shapes and sizes. The first successful barcode was the Universal Product Code (UPC), used for tracking products in stores, which encodes 12 numbers. Other barcodes hold more information, for example the Royal Mail Mailmark (TM) type L barcode – which encodes 26 characters including ID, postcode and delivery point.

QR codes are another kind of barcode, and there are many sizes. A version 4 QR code is 33 x 33 pixels in size and encodes up to 50 characters. A version 40 QR code is 177 x 177 and stores 2,953 bytes, or up to 7,089 digits. This particular QR code is so densely packed it looks like a picture of a snowstorm, and is rarely used because it’s difficult to scan successfully.

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Dr Peter Bentley is a computer scientist and author who is based at University College London. He is the author of books including 10 Short Lessons in Artificial Intelligence and Robotics and Digital Biology: How nature is transforming our technology and our lives.


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